Traditionally, a driving circuit for light emitting diodes (LEDs) raises the operating voltage of the LEDs to enhance the efficiency. However, the voltage of alternate current power is in the form of a sine wave, and raising the operating voltage of the LEDs would lead to reduction of the power factor of the driving circuit. Once the power factor is reduced, power waste exists, which is in contradiction to the well-recognized concept to save energy.
Furthermore, the power factor can be increased by lowering the operating voltage of the LEDs. By doing this, however, the voltage drop between the power source and the LEDs would increase, thus reducing the overall efficiency of the circuits.
Thus, based on the problems of the conventional LED driving methods, the inventor focuses on a new invention of a light emitting device driving circuit.